Increased blood loss after preoperative NSAID. Retrospective study of 186 hip arthroplasties

Evolution of Perioperative Pain Management in Shoulder Arthroplasty

Historically, opioids have been used as a primary conservative treatment for pain related to glenohumeral osteoarthritis (GHOA). However, this practice is concerning as it often leads to overuse, which has contributed to the current epidemic of addiction and overdoses in the United States. Studies have shown that preoperative opioid use is associated with higher complication rates and worse outcomes following surgery, particularly for shoulder arthroplasty. To address these concerns, perioperative pain management for shoulder arthroplasty has evolved over the years to the use of multimodal analgesia.

Perioperative pain management for shoulder surgery: evolving techniques

Improving management of postoperative pain following shoulder surgery is vital for optimizing patient outcomes, length of stay, and decreasing addiction to narcotic medications. Multimodal analgesia (ie, controlling pain via multiple different analgesic methods with differing mechanisms) is an ever-evolving approach to enhancing pain control perioperatively after shoulder surgery. With a variety of options for the shoulder surgeon to turn to, this article succinctly reviews the pros and cons of each approach and proposes a potential pain management algorithm.

Aspirin mono-therapy continuation does not result in more bleeding after knee arthroplasty

PURPOSE

Current clinical practice guidelines sometimes still recommend stopping aspirin five to seven days before knee arthroplasty surgery. Literature regarding multimodal blood management and continuation of anti-platelet therapy in this type of surgery is scant. The study hypothesis was that knee arthroplasty under low-dose aspirin mono-therapy continuation does not cause more total blood loss than knee arthroplasty performed without aspirin. Blood loss would be measured by haemoglobin (Hb) and haematocrit (HTC) levels drop at day 2 or day 4 for patients who benefit from multimodal bleeding control measures.

METHODS

A database of all patients undergoing knee arthroplasty between 2006 and 2014 was analysed. Demographic, surgical and complete blood workup data were collected. A retrospective comparison study analysed both groups in terms of blood loss, by mean calculated blood loss as haemoglobin or haematocrit drop between the preoperative Nadir value and the postoperative day 2 and 4 value. A group of 198 (44 UKA and 154 TKA) patients underwent surgery without interrupting their aspirin therapy for cardiovascular prevention. Mean (SD) age was 71 (8) and the mean (SD) BMI was 29 (5.5) kg/m². The control group consisted of 403 (102 UKA and 301 TKA) patients who were not under aspirin, or any other anti-platelet agent. Mean (SD) age was 65 (10) (p < 0.05) and the mean (SD) BMI was 29 (5.0) kg/m² (n.s.). All patients in the control group were randomly selected.

RESULTS

There were no differences in terms of visible (early) or hidden (late) blood loss as measured by Hb drop in between both groups. There is no difference in transfusion rates.

CONCLUSIONS

Modern multimodal blood management provides sufficient blood loss prevention during and after knee arthroplasty to allow physicians to continue low-dose aspirin mono-therapy for cardiovascular prevention.

LEVEL OF EVIDENCE

III.

Use of a haemostatic matrix (Floseal®) does not reduce blood loss in minimally invasive total knee arthroplasty performed under continued aspirin

BACKGROUND

Aspirin is being used for primary and secondary cardiovascular prevention. It has been proposed that aspirin should be discontinued 5 to 7 days before surgery. However, discontinuation might increase the risk of cardiac and thrombo-embolic co-morbidity. Aspirin also increases the risk of bleeding during and after total knee arthroplasty. This study evaluated if the intra-articular use of a haemostatic matrix (Floseal®) might decrease blood loss in total knee arthroplasty performed under continued aspirin use.

MATERIALS AND METHODS

We retrospectively compared matched pairs in two groups (80 patients in each group). Patients in both groups were taking aspirin: one group was managed with conventional haemostasis (with bovie electrocoagulation), while the other group was treated with an intra-articular haemostatic matrix as an adjunct to electrocoagulation. The outcomes compared were haemoglobin and haematocrit levels at days 2 and 4 after surgery as surrogates for blood loss, transfusion rate, surgical time, and length of stay in the hospital.

RESULTS

No differences were observed between the two groups for haemoglobin and haematocrit levels on days 2 and 4. There were no differences in transfusion rate, surgical time or length of stay in hospital between the two groups.

DISCUSSION

The present study shows that the use of Floseal® has no effect on reducing either visible or hidden blood loss after total knee arthroplasty with peri-operative continuation of aspirin use, as assessed by a drop in haemoglobin or haematocrit.

Safety of peri-operative low-dose aspirin as a part of multimodal venous thromboembolic prophylaxis for total knee and hip arthroplasty

PURPOSE

To examine whether it is safe to continue low-dose (100 mg/day) aspirin perioperatively as a part of standard multimodal venous thromboembolic prophylaxis for total hip arthroplasty (THA) or total knee arthroplasty (TKA).

METHODS

79 women and 60 men aged 52 to 91 years who underwent THA (n=50) or TKA (n=89) were prospectively studied. Preoperatively, 63 of the patients were on 100 mg of aspirin every morning for various medical reasons and continued in the perioperative period, except for the operation day. The remaining 76 patients were controls. Pre- and post-operative haemoglobin levels, postoperative blood drainage, and the amount of reinfused drained blood were recorded. Intra-operative blood loss and operative times were recorded for THA only. These parameters for the aspirin and control groups were compared.

RESULTS

All the parameters, namely blood loss (intraoperative and postoperative), operative time, surgical wound healing, and drop in the haemoglobin level (determined on day 3) did not differ significantly between the 2 groups.

CONCLUSION

It is safe to continue low-dose (100 mg/day) aspirin in the perioperative period as a part of multimodal prophylaxis against deep vein thrombosis.

Pneumatic wound compression after hip fracture surgery did not reduce postoperative blood transfusion: A randomized controlled trial involving 292 fractures

BACKGROUND AND PURPOSE

Patients with fracture of the proximal femur often undergo blood transfusion. A pneumatic compression bandage has been shown to reduce transfusion after primary hip arthroplasty for osteoarthritis. In this randomized trial, we evaluated the efficacy of this bandage following surgery for hip fracture.

PATIENTS AND METHODS

288 patients, 50 years or older with 292 fractured hips treated with hemiarthroplasty or internal fixation (except pinning), were randomized to an experimental group with pneumatic wound compression applied after surgery (n = 138) and a control group with the same dressing but no compression (n = 154). Transfusion threshold was blood hemoglobin below 100 g/L. The primary outcome measures were the number of blood units and the proportion of patients transfused after surgery.

RESULTS

The primary outcome measures were similar in both groups. The mean number of postoperatively transfused blood units was 1.3 in the compression group and 1.1 in the non-compression group. Blood transfusion was given to 84 patients (62%) in the compression group and to 85 patients (55%) in the non-compression group.

INTERPRETATION

Pneumatic wound compression does not reduce the need for transfusion after hip fracture surgery.

Comprehensive preoperative evaluation of platelet function in total knee arthroplasty patients taking diclofenac

The severity and variability of platelet dysfunction in preoperative arthritic patients taking nonsteroidal anti-inflammatory drugs (NSAIDs) have not been well studied previously. We evaluate 30 preoperative patients taking diclofenac (group D) by routine coagulation screen, platelet count, fibrinogen concentration, thrombelastography, and PFA-100 (Dade Behring, Inc, Deerfield, IL)) platelet function analyzer. Ten patients (group P) and 30 healthy volunteers (group N) not taking NSAIDs serve as control. Diclofenac causes significant prolongation of mean PFA-100 closure times (P < .0001). However, the prolongation is highly variable; and up to 33% of patients are still having normal platelet function despite diclofenac consumption. Low body weight is a significant predictor of more severe platelet dysfunction (P < .01). Other tests are not useful. We conclude that not all patients taking NSAIDs have similar platelet dysfunction and that preoperative monitoring with PFA-100 is preferable.

Effects of celecoxib on blood loss, pain, and recovery of function after total knee replacement: a randomized placebo-controlled trial

BACKGROUND

Pain management after surgery has been used as a sales argument for the use of COX-2 inhibitors, but their potential positive and negative effects have not been fully investigated. We thus conducted a controlled evaluation of the effect of celecoxib on perioperative blood loss, pain relief and consumption of analgesics, range of motion, and subjective outcome in conjunction with total knee replacement (TKR).

METHOD

50 patients were randomized to either placebo or celecoxib (200 mg) preoperatively and then twice daily. Total blood loss was calculated by the Hb balance method, taking the patient's pre- and postoperative hemoglobin and blood volume into account. Pain scores (VAS), range of motion, and subjective outcome (KOOS) were monitored postoperatively and during the first year after surgery.

RESULTS

No differences in total, hidden, or drainage blood loss were found between the groups. There were 30% lower pain scores during the first 4 weeks after surgery and lower morphine consumption after surgery in the celecoxib group, while no effect was seen on pain, range of motion, and subjective outcome at the 1 year follow-up.

INTERPRETATION

Celecoxib does not increase perioperative blood loss but reduces pain during the postoperative period after TKR. It is not necessary to discontinue celecoxib before surgery. The postoperative use of celecoxib did not increase range of motion or subjective outcome 1 year after TKR.

The influence of timing of administration on the analgesic efficacy of parecoxib in orthopedic surgery

BACKGROUND

Parecoxib, a selective cyclooxygenase-2 inhibitor, may reduce postoperative pain without increasing bleeding when administered before surgery.

METHODS

We randomly assigned 62 patients scheduled for total hip arthroplasty to the following IV dosing schedule: 1) placebo at induction, at wound closure, and 12 h after induction (control); 2) parecoxib 40 mg at induction, placebo at wound closure, and parecoxib 40 mg 12 h after induction (pre); or, 3) placebo at induction, parecoxib 40 mg at wound closure, and parecoxib 40 mg 12 h after induction (post). Pain scores at rest and with movement were recorded every 4 h for 24 h using a visual analog scale. Treatment side effects were recorded every 4 h. Red cell loss for 5 days after surgery was calculated.

RESULTS

Postoperative pain scores were less in the pre and post groups than in the control group. Postoperative bleeding was similar in the three groups. There were no significant differences between the pre and post groups, nor was their any trend suggesting a preemptive analgesic efficacy from preincision administration of parecoxib. Morphine use in the Postanesthesia Care Unit was reduced in the pre and post groups compared with the control group (14.2 +/- 2.0, and 15.7 +/- 2.0, vs 20.4 +/- 2.3 mg), although the trend was only significant (P < 0.05) in the pre group. The first pain score was also reduced in the pre and post groups compared to the control group (56.1 +/- 7.5 and 64.2 +/- 7.0 vs 78.3 +/- 5), but this was also only significant for the pre group (P = 0.001). The delay for first analgesic demand was increased for both the pre and post group compared to the control group (38 +/- 9 and 28.2 +/- 6.6 vs 18 +/- 6 min) but, again, this was only significant for the pre group (P = 0.05). Twenty-four hour consumption of morphine was similar in the pre (26 +/- 12 mg) and post groups (25 +/- 13 mg); both were significantly less than in the control group (47 +/- 27 mg, P < 0.001).

CONCLUSIONS

Administration of parecoxib before hip arthroplasty did not provide preemptive analgesia. There was a trend towards improved analgesia immediately after surgery with preincision administration, consistent with the expected time course of nonsteroidal antiinflammatory drug's effect. Perioperative parecoxib administration, consisting of two injections spaced 12 h apart, improved postoperative analgesia over the first 24 h without increasing bleeding.

Potential for drug interactions in hospitalized cancer patients

OBJECTIVES

To quantify the frequency of potential drug interactions unrelated to chemotherapy in cancer patients admitted to our institution, and to define risk factors for such interactions.

METHODS

Charts of 100 consecutive hospitalized cancer patients were reviewed. Patients receiving chemotherapy and/or hormone therapy were excluded, as were patients admitted for intensive care. Drug-drug interactions were screened with Drug Interaction Facts software, and manually by the authors. Potential interactions were graded by levels of severity (severe, moderate, minor) and significance (one to five, with one representing the highest level of evidence).

RESULTS

The median age of the patients was 67 years, and the length of hospital stay and the number of drugs per patient were 6 days and eight drugs, respectively. In 63 patients 180 potential interactions were detected. Of the potential interactions, 18.3% were severe, 56.7% were moderate, and 25% were minor. Approximately 7%, 18% and 13% of potential interactions were graded as level 1, 2 and 3, respectively. In multivariate analysis, prescriptions with eight or more drugs (P=0.0004) and six or more days of hospital stay (P=0.014) were independent risk factors for potential interactions.

CONCLUSION

Potential drug interactions are common among hospitalized cancer patients. Length of hospital stay and number of prescribed drugs are risk factors.

[Postoperative analgesia with rofecoxib. How effective is the preoperative application of a 25 mg dose?]

OBJECTIVE

The purpose of this study was to evaluate the analgesic efficacy of 25 mg rofecoxib.

METHODS

In a randomized, prospective double-blind study we investigated the analgesic efficacy of 25 mg rofecoxib in 62 patients scheduled for minor trauma surgery. Patients received 2 h before induction of anesthesia either 25 mg rofecoxib (verum) orally or placebo. These applications were repeated postoperatively after 24 h. Postoperative pain intensity was measured by the numeric rating scale (NRS). All patients were allowed to order piritramid from a PCA-device (bolus 2 mg, lockout 5 min in the recovery room, 15 min on the ward) for 24 h after surgery. 10/20/30 min, as well as 1/2/4/6 h and 24 h after surgery cumulated doses of piritramid, pain scores (0-10) and side effects were recorded.

RESULTS

Pain relief and cumulated doses of piritramid in both groups were comparable at all points in time. There were no significant differences in the incidence of side effects between the two groups.

CONCLUSION

Preoperative application of 25 mg rofecoxib is not effective for postoperative analgesia in patients after minor trauma surgery.

The effect of aspirin on blood loss and transfusion requirements in patients with femoral neck fractures

Although it is widely accepted that aspirin will increase the risk of intra- and post-operative bleeding, clinical studies have not consistently supported this assumption. We aimed to assess the effect of pre-operative aspirin on blood loss and transfusion requirements in patients undergoing emergency fixation of femoral neck fractures. A prospective case-control study was undertaken in patients presenting with femoral neck fractures. Parameters recorded included intra-operative blood loss, post-operative blood loss, transfusion requirements and peri-operative reduction in haemoglobin concentration. Of 89 patients presenting with femoral neck fractures 32 were on long-term aspirin therapy. Pre-operative aspirin ingestion did not significantly affect peri-operative blood loss, or change in haemoglobin concentration or haematocrit. However those patients taking aspirin pre-operatively had a significantly lower haemoglobin concentration and haematocrit and were more likely to be anaemic at presentation than those who were not receiving aspirin. Patients taking aspirin were also more likely to receive blood transfusion post-operatively.

A double-blind study of the effect on hemostasis of nabumetone (Relafen) compared to placebo

A double-blind, placebo-controlled clinical trial comparing the effect on hemostasis of nabumetone (Relafen) to placebo in patients who were about to undergo forefoot surgery was performed. Aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs) are reported to inhibit platelet cyclooxygenase activity, resulting in altered platelet function and thus potentially enhanced bleeding. Nabumetone has been reported to have no effect on platelet aggregation and bleeding time in normal volunteers and in patients who have undergone knee arthroscopy. After fulfilling the inclusion criteria and after a 1-week washout period (acetaminophen controlled), 15 patients were enrolled in the nabumetone group and 15 patients were randomized in the placebo group. Hemostatic parameters [prothrombin time (PT), partial thromboplastin time (PTT), and Ivy bleeding time (IBT)] were assessed at baseline, visit 2, visit 3, and final visit. No meaningful differences were observed between treatment groups in any of the measured hemostatic parameters. No significant adverse events were reported. There was no significant change from baseline for PT, PTT, and IBT in the nabumetone group (PT, p < .06; PTT, p < .64; IBT, p < .17) versus the placebo group (PT, p < .61; PTT, p < .63; IBT, p < .25). The lack of bleeding diathesis and significant prolongation of PT, PTT, or IBT in this study suggests that nabumetone in dosages up to 1000 mg/day can be administered safely in the immediate preoperative period to patients undergoing forefoot surgery.

Standards of laboratory practice: analgesic drug monitoring

Analgesics are the most commonly consumed over-the-counter preparations in the United States. They are used in the treatment of various pain syndromes and other medical conditions. Although analgesics are generally perceived to be safe agents, serious toxicity may occur in the setting of acute overdose, chronic abuse, or overuse. The indications for therapeutic drug monitoring in patients using these medications appropriately is as yet not well defined. The emphasis of this discussion, therefore, is on recommendations for monitoring in situations where toxicity is suspected. Preanalytical, analytical, and practice issues including drug interactions, frequency of monitoring, pertinent ancillary tests, reporting, and special patient groups at risk for toxicity are reviewed. Recent information from a major manufacturer of evacuated tubes arguing against the use of gel tubes for blood collection for drug monitoring is included. Colorimetric/enzymatic/immunoassays for the routine/stat monitoring of acetaminophen and salicylate and diflunisal cross-reactivity with most of the currently used salicylate assays are presented. Achiral and chiral chromatographic assays and newly introduced columns such as restricted access media and/or automated chromatographic systems are reviewed for the analysis of ibuprofen, naproxen, and the recently introduced tramadol. Finally, concepts regarding future directions including drug chirality and chiral analysis are presented.

Risk of haemorrhage from transurethral prostatectomy in acetylsalicylic acid and NSAID-treated patients

Postoperative bleeding in patients who regularly ingest acetylsalicylic acid (ASA) has been reported after several types of surgery. However, data on the influence of ASA on the risk of haemorrhage from transurethral prostatectomy (TUR-P) have been conflicting. We have studied retrospectively the unselected clinical records of all patients undergoing TUR-P in the Department of Urology at Hvidovre Hospital (during 1992-1994) with special focus on the use of ASA and non-steroidal anti-inflammatory drugs (NSAIDs). In total, 457 records were examined: 99 patients on ASA/NSAID received 42 units of blood, while 358 patients free from such medication received 68 units of blood, a significantly smaller amount (p = 0.0390). We conclude that ASA and NSAIDs increase the risk of bleeding during and after TUR-P, and we recommend the withdrawal of these drugs for one week before TUR-P.

Effect of nabumetone on hemostasis during arthroscopic knee surgery

The known effects of commonly used nonsteroidal anti-inflammatory drugs (NSAIDs) on hemostatic parameters have led to concern over their use in the perioperative period. Nabumetone, unlike other NSAIDs, has little effect on collagen-induced platelet aggregation. To evaluate the effect of nabumetone 2000 mg daily on other hemostatic parameters (e.g., bleeding time, prothrombin time, and partial thromboplastin time) in the clinical setting, this double-masked study was conducted in patients with osteoarthritis undergoing arthroscopic knee surgery. After a 1-week placebo washout period, 58 patients were randomized to receive nabumetone and 53 were randomized to receive placebo. They were assessed before surgery (after 1 to 2 weeks of treatment) and again after surgery (after an additional 3 weeks of treatment). The study was designed to have 90% power to show equivalence in bleeding time to within 1.5 minutes, a difference assumed to be of no clinical importance. No meaningful differences were observed between the groups in any of the measured hemostatic parameters. Before surgery, the bleeding time increased by only 0.3 minutes with nabumetone and decreased by 0.2 minutes with placebo. The mean (+/- SD) difference between the groups in change from baseline was 0.5 +/- 0.3 minutes. After surgery, the changes were 0.1 minutes and 0.0 minutes, respectively, and the difference between groups was 0.2 +/- 0.3 minutes. These differences were neither statistically nor clinically significant, and maximum individual increases were similar in each group. Furthermore, there were no reports of abnormal bleeding in the operative knees. The results of this study show that nabumetone had little or no effect on hemostasis and suggest that this drug can be used safely in the perioperative period.

Gastrointestinal endoscopy in patients taking antiplatelet agents and anticoagulants: survey of ASGE members. American Society for Gastrointestinal Endoscopy

BACKGROUND

Gastrointestinal endoscopy is often required in patients taking aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs), or anticoagulants. Because proper guidelines are lacking, we believe that most endoscopists use their own criteria and judgment for stopping and restarting these agents during the periendoscopic period, and the practice varies widely. The aim of our study was to identify these practices among ASGE members.

METHODS

Questionnaires, each containing 22 questions with 157 responses, were sent to 3300 ASGE members, including all Gastroenterology Fellowship Program Directors. One thousand two hundred sixty-nine questionnaires were received and analyzed.

RESULTS

Physicians stopped aspirin and NSAIDs more frequently before colonoscopy (81%) and ERCP (79%) than before upper endoscopy (51%) (p < 0.001). Ninety percent of physicians stopped aspirin and NSAIDs for 10 or fewer days. Only 20% of physicians performed sphincterotomy when aspirin and NSAIDs were not stopped compared with 88% and 85% (p < 0.001 for both) of physicians performing cold biopsies at esophagogastroduodenoscopy and colonoscopy, respectively, and 77% and 69% performing hot biopsies for the same procedures (p < 0.001 for all compared with sphincterotomy). Depending on the indication for anticoagulation, 51% to 60% of physicians stopped warfarin before upper endoscopy; 71% to 82% before colonoscopy; and 26% to 51% of physicians used a "heparin window." All physicians restarted warfarin immediately after diagnostic endoscopy, whereas 80% restarted it 7 or fewer days after therapeutic endoscopy.

CONCLUSIONS

We conclude that a wide variation exists regarding the management of aspirin, NSAIDs, and anticoagulants in the periendoscopic period. There is a definite need for a consensus statement or guidelines for managing patients taking these agents.

Aspirin, a silent risk factor in urology

Aspirin is a widely used drug for its analgetic, antiinflamatory and antipyretic effects as well as for prophylactic effect in cardiovascular diseases. However, an increased number of operative hemorrhagic complications in patients on daily aspirin have been reported, an adverse effect highly relevant in urology. In this review the normal hemostatic mechanism and the chief pharmacological effect of aspirin on hemostasis is described. The literature is reviewed for hemorrhagic complications to aspirin in urology. Few reports indicate that aspirin increases bleeding and need for transfusion following prostatectomy, but no placebo-controlled clinical trials with large patient groups have been carried out. Following prostate biopsy and extracorporeal shock wave lithotripsy aspirin-induced hemorrhagic complications have been reported. Cessation of aspirin ingestion one week prior to invasive urologic procedures and correction of bleeding complications with desmopressin, platelet concentration or fresh whole blood is described.

Enoxaparin. A reappraisal of its pharmacology and clinical applications in the prevention and treatment of thromboembolic disease

Enoxaparin (enoxaparin sodium) is a low molecular weight derivative of unfractionated heparin which has been evaluated for the treatment and prevention of thromboembolic disease. Since a previous review in Drugs, well controlled clinical trials have confirmed the effectiveness of enoxaparin as prophylaxis in patients with a high risk for deep venous thrombosis (DVT), i.e. those undergoing hip or knee replacement surgery. Enoxaparin 30mg twice daily, initiated postoperatively, offers an overall balance of prophylactic efficacy and haemorrhagic tolerability which is superior to that of unfractionated heparin. In comparative clinical trials, this dosage demonstrated either improved efficacy and a similar haemorrhagic profile, or a similar degree of efficacy with a lower rate of haemorrhagic events, compared with unfractionated heparin 5000IU 3 times daily. Limited data indicate that an enoxaparin regimen of 40mg once daily, starting preoperatively, is more effective than unfractionated heparin in patients undergoing hip replacement and has a comparable haemorrhagic profile. In patients with a moderate risk for DVT, enoxaparin is similar to unfractionated heparin in both efficacy and haemorrhagic profile, while preliminary investigations have demonstrated the utility of enoxaparin in the prevention of DVT in elderly, nonsurgical patients. Enoxaparin may also be useful for the treatment of existing DVT and as an anticoagulant in haemodialysis. Thus, enoxaparin is an effective form of prophylaxis for thromboembolic disease in moderate to high risk surgical situations. Recent evidence for improved efficacy, together with a similar incidence of haemorrhagic complications in most situations, may lead to enoxaparin being preferred to unfractionated heparin for the routine prevention of DVT after high risk surgery. Although detailed comparisons with other low molecular weight heparins and antithrombotic agents are required before its relative clinical utility can be fully assessed, enoxaparin is likely to play a significant role in the prophylaxis of thromboembolic disorders.

[Comparison of the effects of ketorolac and aspirin on hemostasis in the rabbit]

OBJECTIVE

Comparison of ketorolac with aspirin and placebo for the antithrombotic activity using the Folts' model of experimental arterial thrombosis and the perioperative blood loss.

STUDY DESIGN

Experimental randomized blinded study anaesthetized, tracheotomized and mechanically ventilated. Carotid blood flow variations were detected by a probe directly inserted around the artery and monitored by an electromagnetic flowmeter. A segment of the exposed carotid artery was de-endothelialized by gently squeezing the artery with a needle holder forceps, and an external constrictor was placed around it (stenosis 60%), to induce cyclic flow reductions (CFR). During 20 min, CFR rate was assessed. Animals were then randomized in 3 groups of 9: ketorolac (K) 1 mg.kg-1, aspirin (A) 10 mg.kg-1 or saline (S), injected intravenously (peripheral ear vein). After drug administration, CFR rate was assessed over 20 min, to determine the potential antithrombotic activity of the drug (curative phase). Thereafter, the opposite carotid artery was injured and stenosed and the occurrence of CFR was assessed over 20 min (preventive phase). The amount of blood loss of a xipho-pubic laparotomy with a spleen section was also measured 30 min after drug administration.

RESULTS

In all untreated animals, CFRs developed with a mean rate of 4 cycles/20 min. Aspirin completely abolished CFR during the curative phase in all rabbits, except in one. No effect was observed during this phase with ketorolac or saline. During the preventive phase, a partial inhibition of CFRs was induced by ketorolac and aspirin. Peri-operative bleeding was not increased significantly by ketorolac or aspirin. Postinjection bleeding-time did not differ between the three groups.

CONCLUSIONS

Ketorolac (1mg.kg-1) has not a strong antithrombotic activity. Ketorolac and aspirin do not increase peri-operative blood loss, and therefore do not seem to strongly interfere with haemostasis in the rabbit.